The utility industry continually tracks and measures physical assets of its networks (e.g., utility wires, utility poles, utility towers), and assesses the current conditions of those assets. With tracking and measurement, the industry seeks to understand information on the current state of the utilities including infringement rights, growth of vegetation, and the like.
Currently, assessment of the utility corridor includes the use of ground crews that walk or drive along the right of way. Companies may also use anything from helicopter flights carrying experts observing assets from the air, to aerial sensor platforms capturing photographic, positional, or other information through the use of remote sensing technology.
Remote sensing technology may have the ability to be the most cost effective while providing pertinent information for assessment of the utility corridor. Cost efficiency may be increased further with capture efficiency. For example, cost efficiency may be increased by using faster aircraft (e.g., fixed wing aircraft), allowing for collection of data over a large number of utility line miles, and the like. Additionally, the use of multiple sensors may aid in collecting large amounts of sensor data, such as, for example, visible cameras, infra-red cameras, and LIDAR scanners.
One direction that the utility industry is developing is modeling assets and features in three dimensions. One base representation of this structure is known as a Method 1 structure model. Currently, this is produced by collecting three-dimensional data points through the use of a LIDAR scanner. By flying low and slow, helicopter systems capture 10 to 20 points per square meter, producing dense point grids. Even at 40 points per grid, however, the average spacing between each point may be 15-cm or about 6 inches. For smaller structures, this may cause measurement inaccuracy.
While lasers have been achieving higher pulse frequencies, there are physical limitations to collecting higher and denser three-dimensional point clouds from a LIDAR scanner. First, the high density point clouds may require flying lower and slower, running counter to a goal of higher efficiency. Second, in order to achieve the higher pulse repetition rates, multiple pulses may need to be in the air simultaneously. Even though light travels extremely quickly, it may take a set time to reach the ground and reflect back to the sensor of the LIDAR scanner. If too many pulses are in the air simultaneously, subsequent pulses may cause interference.
Traditional LIDAR scanner collection methods typically direct and orient the LIDAR collection system straight down (i.e., nadir). This may only allow for 10 to 20 points per square meter on the ground or on a horizontal structure. When vertical structures are present, however, the point density is even further reduced. For a fully vertical surface, the LIDAR scanner may only collect points prior to the vertical structure and on a horizontal surface of the structure at the vertical top. To produce vertical points, the LIDAR scanner may be tilted at an angle, however, now either multiple LIDAR system may need to be installed to capture multiple sides of the structure, or a conical collection path may need to be collected as described in a patent application identified by U.S. Ser. No. 13/797,172 that was filed on Mar. 12, 2013, and issued as U.S. Pat. No. 9,244,272 on Jan. 26, 2016, which is hereby incorporated by reference in its entirety.